Fuel control system and control device therefor or the like

ABSTRACT

Control means having a first passage means for interconnecting a source of fuel to a pilot burner means to produce a small standby flame at the pilot burner means, the control means having second passage means for additionally interconnecting the source of fuel to the pilot burner means to produce a large heater flame at the pilot burner means whereby no fuel is adapted to be interconnected to a main burner means when only a small standby flame exists at the pilot burner means and the source of fuel is adapted to be interconnected to the main burner means when the large heater flame exists at the pilot burner means. A single adjusting means is provided in the passage means for adjusting the fuel flow rate therethrough by substantially infinitely adjusting the flow rate through one of the passages and adjusting the flow rate through the other passage means in substantially a stepped manner.

United States Patent (72] lnventor Francis S. Genbaufle lrwin, Pa. [21] Appl. No 47,356 [22] Filed June 18. I970 [45] Patented Nov. 9, i971 [73] Assignee Robertshaw Controls Company Richmond. Va.

[54] FUEL CONTROL SYSTEM AND CONTROL DEVICE THEREFOR OR THE LIKE 10 Claims, 7 Drawing Figs.

[52] U.S.Cl 431/42. 236/99 [51] int. Cl F23q 9/08 [50] Field of Search 43l/42, 60; 236/99 [56] References Cited UNITED STATES PATENTS 3,341,120 9/1967 Willson A. 236/99 f 59 so 0'':

Primary E.raminerCarroll B Dority, Jr. Auorneys-Auzville Jackson. Jr., Robert L. Marhen and Candor, Candor & Tassone I ABSTRACT: Control means having a first passage means for interconnecting a source of fuel to a pilot burner means to produce a small standby flame at the pilot burner means, the control means having second passage means for additionally interconnecting the source of fuel to the pilot burner means to produce a large heater flame at the pilot burner means whereby no fuel is adapted to be interconnected to a main burner means when only a small standby flame exists at the pilot burner means and the source of fuel is adapted to be interconnected to the main burner means when the large heater flame exists at the pilot burner means. A single adjusting means is provided in the passage means for adjusting the fuel flow rate therethrough by substantially infinitely adjusting the flow rate through one of the passages and adjusting the flow rate through the other passage means in substantially a stepped manner PAIENTEDunv 9 l97l SHEET 1 OF 2 oooooooooooooo INVENTOR. FRANCIS S. GENBAUFFE HIS ATTORNEYS PATENTEnunv 915m 3,619,095

sum 2 0F 2 INVENTOR. FRANCIS S. GENBAUFFE HIS ATTORNEYS FUEL CONTROL SYSTEM AND CONTROL DEVICE THEREFOR OR THE LIKE This invention relates to an improved fuel control system for a fuel-buming apparatus or the like as well as to an improved control device for such a control system or the like.

It is well known from the US. Pat. to Willson, No. 3,344,989, that a control device for a fuel control system can be provided wherein the fuel supplied to a dual rate pilot burner means is controlled in such a manner that when the heat output effect of the main burner means has exceeded a selected output temperature effect thereof, only a small standby flame exists at the pilot burner so that the source of fuel to the main burner means is terminated. However, when a demand for heat is determined, an additional flow of fuel is directed to the pilot burner means to create a large heater flame which is detected by control means so that the source of fuel will be connected to the main burner means to be ignited by the pilot burner means.

Such prior known control means includes a single adjusting key for adjusting the fuel flow rate to the pilot burner means in such a manner that the same is adapted to adjust the standby pilot flame and not the heater flame when the source of fuel is a natural gas source. However, when an LP (liquefied petroleum) source was utilized for such control means, the adjusting key is adapted to adjust only the heater flame and not the standby flame.

However, it has been found according to the teachings of this invention that with such prior known adjusting key means it is relatively difficult to accurately provide the desired adjustment and that with the more variable pressures encountered with natural gas sources, it is necessary to be able to vary the heater flame at such pilot burner means because with gas pressures of 16 to 20 inches of WC. (water column), the heater flame tends to make an adverse hissing sound because the control means is normally utilized with the natural gas source having a pressure of approximately l1 inches W.C. However, the standby flame of the pilot burner means does not require an infinite control to compensate for the variable pressures of the natural gas sources whereby it is found that the fuel flow rate to the pilot burner for standby purposes could be adjusted in a stepped manner.

Accordingly, it is a feature of this invention to provide an improved adjusting means for a pilot burner means wherein the flow of fuel for producing the heater flame can have the rate thereof infinitely variable while the rate of flow to the pilot burner means for producing the standby flame can have a stepped adjustment thereof.

Another feature of this invention is to be able to utilize such an adjusting means with a liquefied petroleum source in such a manner that the same will permit infinite adjustment of the flow rate of fuel to the pilot burner means for the standby flame while providing substantially no adjustment of the flow of fuel for producing the heater flame.

ln particular, one embodiment of this invention provides a first passage means for interconnecting a source of fuel to the pilot burner means to produce a small standby flame at the pilot burner means and a second passage means for additionally interconnecting the source of fuel to the pilot burner means to produce a large heater flame at the pilot burner means. An adjusting means is disposed in the passage means and is adapted to adjust the flow rate therethrough by substantially infinitely adjusting the flow rate through the second passage means while adjusting the flow rate through the first passage means in substantially a stepped manner.

Accordingly, it is an object of this invention to provide an improved fuel control system having one or more of the novel features set forth above or hereinafter shown or described.

Another object of this invention is to provide an improved control device having one or more of the novel features set forth above or hereinafter shown or described.

Other objects, uses and advantages of this invention are apparent from a reading of this description which proceeds with reference to the accompanying drawings forming a part thereof and wherein:

FIG. 1 is a schematic view illustrating the improved fuel control system of this invention utilizing the improved control device of this invention, the control device being illustrated in schematic cross section.

FIG. 2 is an enlarged, fragmentary, cross-sectional view taken on line 22 of FIG. 1 to illustrate the adjusting key of the control device.

FIG. 3 is a view similar to FIG. 2 as taken substantially on line 33 ofFIG. 1.

FIG. 4 is a schematic perspective view illustrating the adjusting key of the control device of FIG. 1 in natural gas, full on" position thereof.

FIG. 5 is a view similar to FIG. 4 and illustrates the adjustment of the adjusting key for a natural gas fuel source.

FIG. 6 is a view similar to FIG. 4 and illustrates the adjusting key in a liquefied petroleum fuel source, full on" position.

FIG. 7 is a view similar to FIG. 6 and illustrates the adjustment of the adjusting key for the liquefied petroleum fuel source. While the various features of this invention are hereinafter described and illustrated as being particularly adapted for providing a fuel control system for a cooking apparatus or the like, it is to be understood that the various features of this invention can be utilized singly or in any combination thereof to provide control means for other devices as desired.

Therefore, this invention is not to be limited to only the embodiment illustrated in the drawings, because the drawings are merely utilized to illustrate one of the wide varieties of this invention.

Referring now to FIG. 1, the improved fuel control system of this invention is generally indicated by the reference numeral l0 and comprises an improved control device 11 of this invention having a housing means 12 provided with an inlet 13 for interconnecting to a fuel source conduit means 14 in a conventional manner so that the control device ll will direct fuel out of a main outlet means 15 thereof into a conduit means 16 that leads to a main burner means 67 for a cooking apparatus or the like, The conduit means 16 has a control valve 17 therein which is provided with a flame detector bulb IS in such a manner that the valve means 17 will not permit fuel to flow therethrough unless the detector bulb l8 detects a large heater flame 19 at a pilot burner means 20. However, when the pilot burner means 20 is only producing a small standby flame 21, the valve means 17 is disposed in a closed condition so that no fuel can be directed through the conduit means 16 to the main burner means 67.

Such a control system and a control device is fully disclosed in the aforementioned US Pat. to Willson, No. 3.344.989, and only the parts thereof believed necessary to fully understand the features of this invention will now be described because reference can be made to such aforementioned US. patent for further details in the structure of the valve means 17, pilot burner means 20 and control device 11.

The inlet passage 13 in the housing 12 of the control device 11 has an on-off valve 22 operated by a selector knob or means 23 of the control device 11 so that when the selector knob 23 is disposed in any on position thereof, the valve 22 is opened and interconnects the fuel source 14 not only to a chamber means 24 in the housing means 12 that leads to the outlet means 15, but also interconnects the fuel source 14 to a passage means 25 that leads to a valve seat 26 adapted to be opened and closed by a ball valve member 27 normally urged to its closed position by a compression spring 28. However, a plunger 29 is adapted to move the ball 27 away from the valve seat 26 in opposition to the force of the compression spring 28 when an associated end 30 of a lever 31 moves downwardly in FIG. 1 so as to interconnect the passage 25 with another passage 32 formed in the housing means 12 and leading to a selector key 33 of this invention and later to be described.

The lever 31 is fulcrumed on the end 34 of an axially movable pin 35 having its axial position in the housing means 12 controlled by the selector knob 23 in the manner fully disclosed in the aforementioned US. patent to Willson. The other end 36 of the lever 31 bears against a movable wall 37 of an expandible and contractable power element 38 having the interior thereof interconnected to a temperature-sensing bulb 39 by a conduit means or capillary tube 40 in a conventional manner so that expansion of the power element 38 causes the lever 31 to pivot on the end 34 of the fulcrum pin 35 in a direction to cause closing of the ball valve 27 whereas a contraction of the power element 38 causes the lever 31 to pivot on the fulcrum pin 35 in a direction to open the ball valve member 27 whereby the condition responsive device 38 in combination with the selector pin 35 is adapted to maintain the temperature of the burner means 67 at a selected temperature effect set by the selector knob 23 as will be apparent hereinafter.

The inlet 13 of the control device 11, in advance of the onoff valve 22, is interconnected to a passage 59 that passes through a suitable filter chamber 60 to a passage 41 that is interconnected to two branch passages 42 and 43 respectively having orifice means 44 and 45 therein and respectively leading to the adjusting key 33.

As illustrated in FIGS. 1 and 4, the adjusting key 33 is rotatably disposed in a suitable bore 46 of the housing means 12 and has an opening 47 interrupting the end 48 thereof and leading to a passage 49 that is interconnected to a conduit 50 that leads to the pilot burner means 20. The opening 47 of the adjusting key 33 is interconnected to the exterior surface 51 thereof by three transverse inlets 52, 53 and 54 with the pair of inlets 53 and 54 being adapted to register with the passages 42 and 43 in the manner illustrated in FIG. 4 while the inlet 52 registers with the passage 32, the inlets 52 and 53 being sub stantially diametrically opposed to each other.

The inlet 53 of the adjusting key 33 has an orifice member 55 therein with an orifice 56 passing therethrough for a purpose hereinafter described.

As illustrated in F l6. 1, the passage 41 leading to the branch passages 42 and 43 for the adjusting key 33 has a restriction or orifice 57 therein.

in one typical embodiment of the control device 11 of this invention, the orifice 57 in the passage 41 can be approximately 0.008 of an inch, the orifice 44 in the passage 42 can be approximately 0.005 of an inch, the orifice 45 in the passage 43 can be approximately 0.006 of an inch, and the orifice 56 in the orifice cup 55 can be approximately 0.01 l of an inch.

The operation of the adjusting key 33 of this invention will now be described.

When the selector key 33 is disposed in its off" position as illustrated in F165. 2 and 3, the inlets 52 and 53 of the selector key 33 are respectively disposed out of fluid communication with the passages 32 and 42 as illustrated in FIG. 3 and the inlet 54 is disposed out of fluid communication with the passage 43 as illustrated in FIG. 2 whereby no fuel is adapted to be supplied to the pilot burner means 20.

However, when the selector key 33 is disposed in its full on" position as illustrated in FIG. 4 for a natural gas fuel source, the inlets 52 and 54 are respectively in full communication with the passages 32 and 43 while the passage 53 is only slightly out of register with the passage 42 whereby the entire flow of fuel from the passage 41 of the housing means 11 wiil be divided by the passages 42 and 43 and be fed respectively into the inlets 53 and 54 and, thus, into the opening 47 of the selector key 33 to be passed by the passage 48 to the pilot burner 20 to maintain the small standby flame 21.

When the control device 11 senses that the output effect of the burner means 67 has fallen below the output effect selected by the selector knob 23, the same operates the lever 31 in such a manner that the ball valve 27 is opened to interconnect the fuel inlet 25 to the passage 32 so that an additional flow of fuel is directed into the opening 47 of the selector key 33 through the inlet 52 to be directed by the passage 49 to the pilot burner 20 whereby the combined standby flow of fuel and the heater flow of fuel from the passage means 32 causes the pilot burner means 20 to create the enlarged heater flame 19 which is detected by the bulb 18 so that the valve means 17 can open and direct the main flow of fuel from the control device 11 to the burner means 67.

As previously stated, when a natural gas fuel source is being utilized by the control device 11 of this invention for the system 10, great variations in pressure are provided whereby if the pressure of fuel exceeds a certain amount, the higher pressure fuel source causes excess hissing noise at the pilot burner means 20 when the same is producing the large heater flame 19 in the manner previously described whereby it is desirable to be able to infinitely vary the flow rate of the additional fuel being fed to the pilot burner means 20 for producing the heater flame 19 whereas the flow of fuel to the pilot burner means 20 for producing just the standby flame 21 can be stepped adjusted for either a low-pressure source or high-pressure source as the case may be.

Thus, it can readily be seen in FIG. 5 that the selector key 33 can be rotated in a clockwise direction from the position illustrated in FIG. 4 in such a manner that the inlet 53 will be moved out of registry with the passage 42 so that the entire flow of fuel through the selector key 33 for producing the standby flame 21 must now pass through the inlet 54 whereby it can be seen that the standby flow of fuel to the pilot burner means 20 has been stepped down for producing the standby flame 21. After the passage or inlet 53 moves out of registry with the passage 42 in the manner illustrated in FIG. 5, further clockwise movement of the selector key 33 will begin to cause infinite control of the rate of fuel flow through the inlet 52 as the inlet 52 begins to close off from the passage 32 as illustrated in FIG. 5 whereby infinite control will be provided for the flow of fuel that creates the large heater flame 19.

When the fuel source is a liquefied petroleum fuel source, the pressure of the fuel being fed the fuel source conduit 14 is controlled by an external pressure regulator in advance of the control means 11 whereby there is no great variation in the pressures of liquefied petroleum fuel sources in contrast to the variations in pressures of natural gas fuel sources.

Thus, with liquefied petroleum fuel sources, the selector key 33 merely need provide means for adjusting the standby flame 21 so that the same will not be too large to cause false detection by the bulb 18 to open the valve 17 for a runaway condition of the system 10.

Thus, with the selector key 33 disposed in the full "on" position illustrated in FIG. 6 for a liquefied petroleum fuel source, it can be seen that the inlet 54 is completely out of registry with the passage 43 while the inlet 52 is in full registry with the passage 42 so that the entire flow of fuel for producing the standby flame 21 passes through the inlet 52 of the selector key 33. Similarly, the inlet 53 is disposed in communication with the passage 32 so that the heater flow of fuel to the pilot burner means 20 for producing the heater flame 19 will pass through the selector key 33. In order to adjust the standby flame 21, the selector key 33 is rotated in a counterclockwise direction from the position illustrated in FIG. 6 to the position illustrated in H6. 7 whereby the inlet 52 begins to cut off from the passage 42 to provide infinite adjustment for the standby flame 21 while the inlet 53 remains substantially in full communication with the passage 32 so that no adjustment of the flow rate for producing the heater flame 19 is provided by the adjusting key 33.

Therefore, it can be seen that the selector key 33 of this invention provides a single adjustment means for controlling the pilot burner means 20 for either a natural gas fuel source or a liquefied petroleum fuel source in the unique manner previously described.

Thus, this invention not only provides an improved fuel control system, but also this invention provides an improved C011- trol device for such a system or the like.

While the form of the invention now preferred has been disclosed as required by the statutes, other forms may be utilized all coming within the scope of the claims which follow.

What is claimed is:

1. A control system comprising a main burner means, a pilot burner means, a source of fuel, control means for connecting and disconnecting said source of fuel to and from said main burner means, first passage means for interconnecting said source of fuel to said pilot burner means to produce a small standby flame at said pilot burner means, second passage means for additionally interconnecting said source of fuel to said pilot burner means to produce a large heater flame at said pilot burner means, control means disconnecting said source of fuel from said main burner means only when said small standby flame exists at said pilot burner means and interconnecting said source of fuel to said main burner means when said heater flame exists at said pilot burner means, and a single adjusting means in said passage means adapted for adjusting the flow rate therethrough by substantially infinitely adjusting the flow rate through one of said passage means and adjusting the flow rate through the other passage means in substantially a stepped manner.

2. A control system as set forth in claim 1 wherein said adjusting means is adapted to substantially infinitely vary the flow rate through said one passage means after said adjusting means has varied the flow rate through said other passage means in said stepped manner.

3. A control system as set forth in claim 2 wherein said one passage means comprises said second passage means and said other passage means comprises said first passage means.

4. A control system as set forth in claim 3 wherein said adjusting means is also adapted to substantially infinitely vary the flow rate through said first passage means while substantially not affecting the flow rate through said second passage means.

5. A control system as set forth in claim 4 wherein said adjusting means is normally adapted to step adjust the flow rate through said first passage means and infinitely vary the flow rate through said second passage means when said source of fuel comprises a natural gas source and said adjusting means is normally adapted to infinitely vary the flow rate through said first passage means and not affect the flow rate through said second passage means when said source of fuel comprises a liquified petroleum source.

6. A control system as set forth in claim 5 wherein said adjusting means comprises an adjusting key which when rotated in one direction is adapted to control said passage means for said natural gas source and when rotated in the opposite direction is adapted to control said passage means for said liquified petroleum source.

7. A control system as set forth in claim 1 wherein said other passage means includes two passages leading from said source to said pilot burner means, said adjusting means being adapted to cause stepped flow change through said other passage means by selectively opening and closing one of said two passages.

8. A control system as set forth in claim 7 wherein said one passage means comprises a single passage leading from said source to said pilot burner means, said adjusting means being adapted to cause infinite flow change through said one passage means by throttling the flow through said single passage 9. A control system as set forth in claim 8 wherein said adjusting means comprises an adjusting key having a common opening leading to said pilot burner means, said adjusting key having inlets for interconnecting said opening with said two passages and a single inlet for interconnecting said opening with said single passage.

10. A control system as set forth in claim 9 wherein the one inlet of said pair of inlets of said adjusting key that is adapted to register with said one passage of said two passages carries an orifice member so that flow through that inlet must pass through said orifice member.

i t i i 

1. A control system comprising a main burner means, a pilot burner means, a source of fuel, control means for connecting and disconnecting said source of fuel to and from said main burner means, first passage means for interconnecting said source of fuel to said pilot burner means to produce a small standby flame at said pilot burner means, second passage means for additionally interconnecting said source of fuel to said pilot burner means to produce a large heater flame at said pilot burner means, said control means disconnecting said source of fuel from said main burner means only when said small standby flame exists at said pilot burner means and interconnecting said source of fuel to said main burner means when said heater flame exists at said pilot burner means, and a single adjusting means in said passage means adapted for adjusting the flow rate therethrough by substantially infinitely adjusting the flow rate through one of said passage means and adjusting the flow rate through the other passage means in substantially a stepped manner.
 2. A control system as set forth in claim 1 wherein said adjusting means is adapted to substantially infinitely vary the flow rate through said one passage means after said adjusting means has varied the flow rate through said other passage means in said stepped manner.
 3. A control system as set forth in claim 2 wherein said one passage means comprises said second passage means and said other passage means comprises said first passage means.
 4. A control system as set forth in claim 3 wherein said adjusting means is also adapted to substantially infinitely vary the flow rate through said first passage means while substantially not affecting the flow rate through said second passage means.
 5. A control system as seT forth in claim 4 wherein said adjusting means is normally adapted to step adjust the flow rate through said first passage means and infinitely vary the flow rate through said second passage means when said source of fuel comprises a natural gas source and said adjusting means is normally adapted to infinitely vary the flow rate through said first passage means and not affect the flow rate through said second passage means when said source of fuel comprises a liquified petroleum source.
 6. A control system as set forth in claim 5 wherein said adjusting means comprises an adjusting key which when rotated in one direction is adapted to control said passage means for said natural gas source and when rotated in the opposite direction is adapted to control said passage means for said liquified petroleum source.
 7. A control system as set forth in claim 1 wherein said other passage means includes two passages leading from said source to said pilot burner means, said adjusting means being adapted to cause stepped flow change through said other passage means by selectively opening and closing one of said two passages.
 8. A control system as set forth in claim 7 wherein said one passage means comprises a single passage leading from said source to said pilot burner means, said adjusting means being adapted to cause infinite flow change through said one passage means by throttling the flow through said single passage.
 9. A control system as set forth in claim 8 wherein said adjusting means comprises an adjusting key having a common opening leading to said pilot burner means, said adjusting key having inlets for interconnecting said opening with said two passages and a single inlet for interconnecting said opening with said single passage.
 10. A control system as set forth in claim 9 wherein the one inlet of said pair of inlets of said adjusting key that is adapted to register with said one passage of said two passages carries an orifice member so that flow through that inlet must pass through said orifice member. 